Top Reasons for Keeping Cats Indoors

To Protect Wildlife and Humans

Outdoor domestic cats are a recognized threat to global biodiversity. Cats have contributed to the extinction of 33 species and continue to adversely impact a wide variety of other species, including those at risk of extinction. The International Union for the Conservation of Nature (IUCN) lists domestic cats as one of the world’s worst non-native invasive species.

The top human-caused threat to birds in the U.S. and Canada is by domestic cats, which number well over 100 million in the United States. Cats kill approximately 2.4 billion birds every year in the U.S. alone.

A wide variety of wildlife, including birds, mammals, reptiles and insects are killed by cats. Studies conducted at the Wildlife Center of Virginia found that 84 different species of wildlife were brought to the center after being injured by a cat — 21 species of mammals and 62 bird species.

Even if the bird or other animal escapes, they often die later. Cats carry bacteria in their mouths that overwhelm small animal immune systems. Injuries and a high degree of stress usually kill a small bird or mammal even after it escapes the cat.

A significant number of wildlife victims are parents defending nests and fledglings, meaning that not only was the individual bird lost, but also more than likely her young as well.

The mere presence of cats outdoors is enough to cause significant impacts to birds. Because cats are recognizable predators, even brief appearances near avian nest sites leads to at least a doubling in lethal nest predation of eggs and young birds by third-party animals and reduces by a third the amount of food brought to nestlings.

House cats are considered "super predators" because:

they are an introduced predator (so wildlife has not evolved to defend themselves)

they exist in unnaturally large numbers, far greater than any natural predator

they are prolific breeders and tolerate other cats in their territories, so large numbers are maintained

many have a constant food source and are often more fit than natural predators

Cats are the most common spreaders of the parasite toxoplasmosis gondii. Infection can lead to neurological problems, and sometimes death, in both wildlife and humans. Cats have been found to spread the disease widely, even in remote areas, through defecation. 25% of humans are infected, which has resulted in increased risk of eye lesions, deafness, seizures, mental retardation, blindness, schizophrenia, Alzheimer’s Disease, autism, obsessive compulsive disorder, memory loss, multi-organ failure, and even death. As many as 74% of all domestic cats in the United States will be infected by T. gondii during their lifetimes.

Cats are the top carrier of rabies among domestic animals in the United States and have outpaced dogs for decades. If an animal is bit by another rabid animal it usually dies quickly. For humans, it is also fatal if left untreated.

To Protect the Cats Themselves

Cats who are kept indoors live an average of 12 to 15 years - outdoor cats live on average 3 to 10 years (depending on the risks in the environment).

Outdoor cats are at risk of:

getting wounded in fights with other animals (many times resulting in dangerous abscesses)

being hit by cars (an estimated 5.4 million are hit a year)

eaten by a predator such as an owl, raptor, coyote or dog

killed by inadvertently ingesting poisons such as antifreeze, rat poisoning or toxic plants

It’s harder for owners to identify health problems early (such as urinary tract disorder, renal failure due to old age, genetics or ingesting poison, and disease), before they become life threatening. When a cat is sick or injured, their natural instinct is to hide in silence because this is their primary defense mechanism from predators.

"Cats have been introduced into new habitats across the globe with terrible results. Outdoors, cats are a non-native and invasive species that threaten birds and other wildlife, disrupt ecosystems, and spread diseases" American Bird Conservancy.